Japanese Patent Application Publication No. 2010-44363 discloses a tandem type color printer in which a plurality of cartridges is detachably attached to a main casing. In such a type of color printer, a drawer unit and a positioning mechanism are provided. The drawer unit is configured to receive a plurality of cartridges, and can be pulled out of and pushed into a main frame. The drawer unit is subjected to positioning at a predetermined position in the main frame by the positioning mechanism.